How long is Ripley and the Colonial Marines on LV 426 in Aliens? Ripley states that it took 1 Xeno less than 24 hours to destroy the Nostromo ship and crew and considering the fully formed nest, including Queen, has upwards of 50 Xeno's the time spent on LV 426 couldn't have been much longer? I was wondering as Ripleys reason to go was based on her recurring nightmares and she only seems to get a quick nap while there.
Based on the original script, from the point that Ripley wakes up from hypersleep (ship-time 06:00-ish) to the point that they return to the Sulaco appears to be a little over 26 hours, based on Apone's orders to his men to get ready, his timescale to load the drop-ship, Bishop's projection over how long the reactor will take to blow, Hick's conversation with Ripley and Ripley checking her watch after napping. I've estimated an hour from that point until the return takes place.
RIPLEY: How long until it blows?
BISHOP: I'm projecting total systems failure in a little under four hours. The blast radius will be about thirty kilometers. About equal to ten megatons.
BISHOP: This duct runs almost to the up-link assembly. One hundred eighty meters. Say, forty minutes to crawl down there. One hour to patch in and align the antenna. Thirty minutes to prep the ship, then about fifty minutes flight time.
HICKS: How long since you slept? Twenty-four hours?
INT. OPERATING ROOM - TIGHT ON RIPLEY - MED LAB:
as she awakens with a start. She checks her watch... an hour has passed.
Assuming they had an hour or two to get woken up, eat and shower (and since prep and dust-off take 7 hours and assuming flight-time is around 1 hour) that means that they were on the planet for a combined time of approximately 16 hours.